Method for producing high-strength pipeline steel plate

Abstract

The present invention discloses a method for producing high-strength pipeline steel plates. The production method comprises: heating the steel billet, with the soaking zone temperature being 1150-1220°C and the dwell time being 25-45 minutes; firstly performing recrystallization zone rolling at a rolling temperature of 950-1050°C to obtain an intermediate billet with a thickness of 2t-6t; then performing non-recrystallization zone rolling at a final rolling temperature of T3-5°C to T3+15°C; the hot-rolled steel plate enters an ultra-fast cooling system for water cooling, and the final cooling temperature is controlled according to the measured C content; after exiting the ultra-fast cooling system, the steel plate is naturally air-cooled to room temperature on a cooling bed to obtain a finished steel plate. The present invention can not only meet the strict requirements of pipeline steel for tensile strength, yield strength, yield strength ratio, impact toughness, drop weight tearing performance, etc., but also reduce the strength difference between the same plate and the strength difference between different plates. In addition, the alloy content is low and the production efficiency is high.

Description

Technical Field

[0001] The present invention belongs to the technical field of steel material preparation, and relates to a method for producing a steel plate of high-strength pipeline steel, in particular to a method for producing X80 grade pipeline steel. Background Art

[0002] As a fast, economical and effective way to transport oil and natural gas, pipeline transportation is listed as one of the five major modern transportation modes, along with railway transportation, road transportation, water transportation and air transportation.

[0003] Pipeline steel is a type of steel with specialized requirements for pipelines used to transport oil and natural gas. It is rolled from billets into steel plates, which are then welded together to form pipes for oil and gas transportation. Due to the demanding application conditions, pipeline steel plates are typically required to meet strict tensile strength and yield strength limits, as well as strict requirements for yield strength ratio, impact toughness, and drop weight tear resistance, making production extremely challenging.

[0004] In particular, for pipeline steel used in harsh service environments such as geographical and climatic conditions, the level of mechanical strength is no longer the most important issue. Instead, the uniformity of the steel plate's performance, such as strength differences between the same and different steel plates, is the most serious problem faced in pipeline steel production.

[0005] In the existing production of pipeline steel: one type of technology, represented by CN114774658A, uses components with high alloy contents such as Ni, V, and Cu. Although it can improve the uniformity of the microstructure and performance of pipeline steel to a certain extent, it leads to increased production costs; one type of technology, represented by CN103993240A, uses a stacking process, which can also improve performance uniformity, but stacking leads to long production time and cannot meet the current requirements of efficient production; and another type of technology, represented by CN110343936A, solves the problem of improving the difference in transverse and longitudinal strength, but cannot improve the performance uniformity of the product, such as the difference in strength between the same plate and the difference in strength between different plates.

[0006] In summary, in the field of pipeline steel plates, how to improve the technical deficiencies in performance uniformity (including strength differences between the same plate and strength differences between different plates) while improving strength, and overcoming problems such as high alloy content and low production efficiency, is an important task in this field. Summary of the Invention

[0007] In order to solve the problems in the prior art, an object of the present invention is to provide a method for producing a steel plate of high-strength pipeline steel.

[0008] To achieve the above-mentioned object, one embodiment of the present invention provides a method for producing a high-strength pipeline steel plate. The chemical composition of the pipeline steel comprises, by mass percentage, the following: C 0.050-0.080%, Si 0.11-0.18%, Mn 1.51-1.59%, Cr 0.01-0.08%, Ni 0.01-0.08%, Cu 0.01-0.08%, Nb 0.024-0.036%, Ti 0.011-0.019%, Al 0.021-0.049%, P ≤ 0.020%, S ≤ 0.0050%, N ≤ 0.0055%, and the remainder is iron and unavoidable impurities;

[0009] The production method comprises:

[0010] The steel billet with a thickness of ≤320mm is heated in a heating furnace with a soaking zone temperature of 1150-1220℃ and a dwell time of 25-45min.

[0011] After leaving the heating furnace, the steel slab is first rolled in the recrystallization zone at a rolling temperature of 950-1050°C to obtain an intermediate slab with a thickness of 2t-6t; then rolled in the non-recrystallization zone at a finishing temperature of T3-5°C to T3+15°C to obtain a hot-rolled steel plate with a thickness of 6-60mm; wherein T3 = 910-310[C]-80[Mn]-15[Cr]-80[Mo];

[0012] The hot rolled steel plate enters the ultra-fast cooling system for water cooling, and the final cooling temperature is controlled according to the measured C content; when 0.055%≤C≤0.060%, the final cooling temperature is T4-290℃~T4-270℃; when 0.050%≤C<0.055%, the final cooling temperature is T4-310℃~T4-290℃; when 0.045%≤C<0.050%, the final cooling temperature is T4-310℃~T4-290℃; when 0.045%≤C<0.050%, the final cooling temperature is T4-310℃~T4-290℃. T4-330℃~T4-310℃; when 0.040%≤C<0.045%, the final cooling temperature is T4-350℃~T4-330℃; when 0.030%≤C<0.040%, the final cooling temperature is T4-370℃~T4-350℃; where T4=830-270[C]-90[Mn]-37[Ni]-70[Cr]-83[Mo];

[0013] After leaving the ultra-fast cooling system, the steel plate is naturally air-cooled to room temperature on the cooling bed to obtain the finished steel plate;

[0014] Among them, [C], [Mn], [Cr], [Mo], and [Ni] are the mass percentages of C, Mn, Cr, Mo, and Ni in pipeline steel, respectively.

[0015] Preferably, the chemical composition of the pipeline steel includes, by mass percentage, P 0.0090-0.0140%, S 0.0010-0.0038%, and N 0.0021-0.0051%.

[0016] Preferably, the chemical composition of the pipeline steel is:

[0017] CEV = [C] + [Mn] / 6 + ( [Cr] + [Mo] + [V]) / 5 + ( [Cu] + [Ni]) / 15 is 0.352 to 0.420;

[0018] Among them, [C], [Mn], [Cr], [Mo], [V], [Cu], and [Ni] are the mass percentages of C, Mn, Cr, Mo, V, Cu, and Ni in pipeline steel, respectively.

[0019] Preferably, during the water cooling of the hot rolled steel plate in the ultra-fast cooling system:

[0020] If the thickness t of the hot-rolled steel plate is 6 to 30 mm, the cooling water volume per unit length of the head and tail low-temperature sections of the steel plate is controlled to be smaller than the cooling water volume per unit length Q of the middle section of the steel plate;

[0021] If the thickness of the hot-rolled steel plate is greater than 30 mm, the amount of cooling water per unit length of the steel plate remains constant along the longitudinal direction.

[0022] Preferably, the thickness t of the hot-rolled steel plate is 6 to 30 mm;

[0023] The head low-temperature section is divided into the 1st to nth sub-sections arranged in sequence from the head, and the tail low-temperature section is divided into the 1st to mth sub-sections arranged in sequence from the tail, n≥2, m≥2;

[0024] During water cooling on the ultra-fast cooling system, the cooling water volume per unit length of the 1st to nth sub-sections of the head low-temperature section is controlled to increase successively, and the cooling water volume per unit length of the 1st to mth sub-sections of the tail low-temperature section is controlled to increase successively.

[0025] Preferably, the production method further comprises:

[0026] Before entering the ultra-fast cooling system, the temperature of the hot-rolled steel plate is measured at intervals of 0.2 to 0.5 m along the longitudinal direction from the beginning to the end, and the temperature measurement results are obtained;

[0027] The vertical position is D T ~(DD W ) is used to calculate the average temperature T in the middle of the area. Z ; Where D is the longitudinal length of the hot-rolled steel plate, D T The value is between 1.5 and 3.5 m, D WThe value is between 1.5 and 3.5m;

[0028] Lower the temperature below T Z -T T The head section of the steel plate is used as the head low temperature section, and the temperature is lower than T Z -T W The tail section of the steel plate is taken as the tail low-temperature section, and the rest of the sections except the head low-temperature section and the tail low-temperature section are taken as the middle section; wherein, T T and T W Each value is any value between 20 and 50°C.

[0029] Preferably, the transverse width W of the hot-rolled steel plate is;

[0030] In the step of "taking points at intervals of 0.2 to 0.5 m along the longitudinal direction of the hot-rolled steel plate from the beginning to the end for temperature measurement", points are taken in the W / 3 to 2W / 3 area in the transverse middle of the hot-rolled steel plate for temperature measurement, and all temperature measurement points are arranged in a straight line along the longitudinal direction.

[0031] Preferably, D T and D W The values ​​of decrease in a step-by-step manner as t increases;

[0032] When t<10mm, 2.75m<D T ≤3.5m, 2.75m<D W ≤3.5m;

[0033] When 10mm≤t<15mm, 2.25m<D T ≤2.75m, 2.25m<D W ≤2.75m;

[0034] When 15mm≤t≤30mm, 1.5m<D T ≤2.25m, 1.5m<D W ≤2.25m.

[0035] Preferably, in the step of "before entering the ultra-fast cooling system, measuring the temperature of the hot-rolled steel plate at points spaced 0.2 to 0.5 m from the beginning to the end in the longitudinal direction to obtain temperature measurement results":

[0036] Take temperature measurements at points with a distance of 0.2 to 0.5 m from the beginning to the end of the hot-rolled steel plate in the longitudinal direction;

[0037] Remove outliers and get the temperature measurement results;

[0038] Among them, if the temperature difference between one temperature measuring point and the temperature of an adjacent temperature measuring point reaches T X1 Above, the temperature difference with another adjacent temperature measuring point is less than T X2When , the temperature measurement point is the abnormal value; wherein, T X1 The value is between 60 and 80℃, T X2 The value is between 5 and 15 degrees Celsius;

[0039] Or, if the temperature difference between one temperature measuring point and the temperature of two adjacent temperature measuring points reaches T X3 When the temperature is above , the temperature measurement point is the abnormal value; wherein, T X3 The value is between 60 and 80℃;

[0040] Alternatively, all the temperature measurement points are used as the data basis, and the temperature is used as the dependent variable and the position is used as the independent variable to fit the temperature curve of the entire longitudinal length of the steel plate. If the temperature of a temperature measurement point deviates from the temperature curve by T X4 When the value is above , the temperature measurement point is determined to be an abnormal value and removed; X4 The value is between 60 and 80℃.

[0041] Preferably, the step of "lowering the temperature below T Z -T T The head section of the steel plate is used as the head low temperature section, and the temperature is lower than T Z -T W The tail section of the steel plate is used as the tail low-temperature section, and the remaining sections except the head low-temperature section and the tail low-temperature section are used as the middle section.

[0042] Starting from the beginning in the longitudinal direction of the steel plate, when the temperature of the temperature measuring point close to the plate head among the two adjacent temperature measuring points is less than T Z -T T , and the temperature of a temperature measuring point far away from the plate head reaches T Z -T T When the temperature is above 0.05, one of the two adjacent temperature measurement points is used as the dividing line to divide the longitudinally arranged head low temperature section and middle section;

[0043] Starting from the tail in the longitudinal direction of the steel plate, when the temperature of the temperature measuring point near the tail of the plate is lower than T Z -T W , and the temperature of a temperature measuring point far away from the tail reaches T Z -T W When the temperature is above 0.05, one of the two adjacent temperature measuring points is used as the dividing line to divide the longitudinally arranged tail low-temperature section and middle section.

[0044] Preferably, the step of "lowering the temperature below T Z -T T The head section of the steel plate is used as the head low temperature section, and the temperature is lower than T Z -T WThe tail section of the steel plate is used as the tail low-temperature section, and the remaining sections except the head low-temperature section and the tail low-temperature section are used as the middle section.

[0045] According to the temperature measurement results, the temperature curve of the entire longitudinal length of the steel plate is fitted with temperature as the dependent variable and position as the independent variable;

[0046] Confirm that within the range of 0 to D / 2, T on the temperature curve Z -T T The corresponding position D TF , and confirm that within the range of D / 2 to D, T on the temperature curve Z -T W The corresponding position D WF ;

[0047] Position D TF and position D WF To divide the boundaries, the steel plate is divided into a head low-temperature section, a middle section and a tail low-temperature section arranged in sequence from the beginning to the end in the longitudinal direction.

[0048] Preferably, in the step “the head low-temperature section is divided into the 1st to nth sub-sections arranged sequentially from the head, and the tail low-temperature section is divided into the 1st to mth sub-sections arranged sequentially from the tail, n≥2, m≥2”:

[0049] The temperature span of each sub-section does not exceed T Tk , divide the head low temperature section into n sub-sections;

[0050] The temperature span of each sub-section does not exceed T Wk , divide the tail low temperature section into m sub-sections;

[0051] Among them, T Tk The highest temperature T among all the temperature measurement points in the low temperature section of the head T1 and the lowest temperature section T T0 Difference T T1 -T T0 1 / n of the temperature curve, or the highest temperature T in the low temperature section of the head Z -T T and the lowest temperature section T T0 'Difference T Z -T T -T T0 ', or the predetermined value T of the temperature span n ;

[0052] T Wk The highest temperature T among all the temperature measurement points in the tail low temperature section W1 and the lowest temperature section T W0 Difference T W1 -TW0 1 / m, or the highest temperature T in the tail low temperature section of the temperature curve Z -T W and the lowest temperature section T W0 'Difference T Z -T W -T W0 '1 / m, or the predetermined value of temperature span T m ;

[0053] The temperature curve is obtained by fitting based on the temperature measurement results, with temperature as the dependent variable and position as the independent variable;

[0054] T n and T m Each value is any value between 5 and 20°C.

[0055] Preferably, in the step of "during the water cooling on the ultra-fast cooling system, controlling the cooling water volume per unit length of the 1st to nth sub-sections of the head low-temperature section to increase sequentially, and controlling the cooling water volume per unit length of the 1st to mth sub-sections of the tail low-temperature section to increase sequentially",

[0056] The cooling water volume per unit length of the 1st to nth sub-sections is k1 to k n times; among them, k1~k n The value ranges from 0.55 to 0.98;

[0057] The cooling water volume per unit length of the 1st to mth sub-sections is K1 to K m times; among them, K1~K m The value ranges from 0.50 to 0.95.

[0058] Preferably, k1~k n The value of K1~K m The values ​​of increase with the increase of t;

[0059] When t is less than 10 mm, k1~k n The value ranges from 0.55 to 0.85, K1 to K m The value ranges from 0.50 to 0.80;

[0060] When 10mm≤t<15mm, k1~k n The value ranges from 0.70 to 0.90, K1 to K m The value ranges from 0.65 to 0.85;

[0061] When 15mm≤t≤30mm, k1~k n The value ranges from 0.80 to 0.98, K1 to K mThe value is 0.75-0.95. Preferably, when t is less than 10 mm, n=m=3, k1 is 0.55-0.65, k2 is 0.65-0.75, k3 is 0.75-0.85, K1 is 0.50-0.60, K2 is 0.60-0.70, and K3 is 0.70-0.80;

[0062] When 10mm≤t<15mm, n=m=3, k1 is between 0.70~0.80, k2 is between 0.80~0.85, k3 is between 0.85~0.90, K1 is between 0.65~0.75, K2 is between 0.75~0.80, and K3 is between 0.80~0.85;

[0063] When 15mm≤t≤30mm, n=m=3, k1 is between 0.80~0.87, k2 is between 0.87~0.92, k3 is between 0.92~0.98, K1 is between 0.75~0.85, K2 is between 0.85~0.90, and K3 is between 0.90~0.95.

[0064] Compared with the prior art, the present invention has the following advantages: on the one hand, the chemical composition does not contain the expensive metal V, and the addition of alloys such as Ni, Cu, and Mo is low. Harmful elements such as P, S, and N do not need to be controlled to ultra-low levels, thus facilitating easy production and low cost. On the other hand, in terms of process, by controlling the temperature and other parameters during heating, rolling, and cooling, the differences in the steel plate structure and properties caused by temperature differences can be greatly reduced, as well as the performance fluctuations caused by slight differences in the composition of pipeline steels of the same grade. Thus, while ensuring the tensile strength, yield strength, yield strength ratio, impact toughness, and drop weight tear resistance of the steel plate, the uniformity of the performance of the same plate can be guaranteed, as well as the uniformity and stability of the performance between different steel plates of the same grade, thereby achieving control of the strength differences between different plates of the same grade. On the other hand, the present invention avoids the chemical composition with high alloy content and inefficient processes such as stacking in the prior art, with the advantages of low cost and high efficiency, which can solve the difficulties in the field of pipeline steel plate production and greatly promote the development of the pipeline industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] Figure 1 It is a flowchart of a production method according to one embodiment of the present invention;

[0066] Figure 2 is a schematic longitudinal top view of a steel plate in a production method according to one embodiment of the present invention;

[0067] Figure 3 Schematic diagram of a temperature curve fitted in a production method according to one embodiment of the present invention. DETAILED DESCRIPTION

[0068] The technical solution of the present invention is further introduced below in conjunction with specific implementation methods.

[0069] The present invention provides a method for producing steel plates for high-strength pipeline steel, which can not only meet the strict requirements of pipeline steel in terms of tensile strength, yield strength, yield strength ratio, impact toughness, drop weight tearing performance, etc., but also greatly improve performance uniformity (including strength difference between the same plate and strength difference between different plates). Moreover, compared with the existing technology, it can also greatly reduce the alloy content, reduce production costs, avoid long processes and time-consuming procedures, and improve production efficiency.

[0070] Specifically, in terms of chemical composition, the chemical composition of the pipeline steel includes, by mass percentage, C 0.030-0.060%, Si 0.16-0.24%, Mn 1.61-1.69%, Cr 0.14-0.18%, Ni 0.11-0.16%, Cu 0.01-0.08%, Mo 0.09-0.13%, Nb 0.051-0.065%, Ti 0.011-0.019%, Al 0.021-0.049%, P≤0.020%, S≤0.0050%, N≤0.0055%, and the rest are iron and unavoidable impurities.

[0071] The following is an introduction to the functions and mechanisms of each element in the above chemical composition.

[0072] C: The most economical strengthening element in steel, it provides solid solution strengthening and can form carbides with Nb, Ti, Cr, Mo, and other elements, providing precipitation strengthening. Increasing carbon content improves the strength and hardness of pipeline steel, but excessive carbon content can degrade low-temperature toughness and weldability. Therefore, the ideal carbon content is 0.030-0.060%.

[0073] Si: It has a solid solution strengthening effect in steel. Too much silicon can easily produce Fe2SiO4 on the surface of the slab, which is not conducive to the control of the surface quality of the steel plate. Therefore, the selected content is 0.16-0.24%.

[0074] Mn: It plays a role of solid solution strengthening in steel, improving strength and hardness. Reasonable manganese content can ensure the strength of pipeline steel at a low cost, but too much manganese will cause center segregation of the ingot, which will have a great damage to toughness. Therefore, the selected manganese content is 1.61-1.69%.

[0075] Cr: Cr acts as a solid solution strengthening element in steel. Also, as a ferrite-forming element, it can produce more acicular ferrite in high-niobium steels. However, excessive Cr content increases the microhardness of pipeline steels and reduces low-temperature toughness. Therefore, the ideal content is 0.14-0.18%.

[0076] Ni: It acts as a solid solution strengthening agent in steel, increasing its strength without significantly increasing its hardness. It also contributes to its low-temperature toughness. However, if the content is too high, the alloy cost increases. Therefore, the ideal content is 0.11-0.16%.

[0077] Cu: It promotes niobium precipitation and compensates for the strength loss caused by the decrease in carbon content. Adding a certain amount of nickel along with copper can effectively suppress surface cracks in continuous casting billets. However, high content can negatively impact weldability. Therefore, the ideal content is 0.01-0.08%.

[0078] Mo: Mo significantly improves the hardenability of steel, delays ferrite transformation, and produces acicular ferrite, which is beneficial for improving the strength and toughness of pipeline steel. However, Mo increases the number of MA components, which is detrimental to toughness. Furthermore, excessive Mo content significantly increases alloy cost. Therefore, the Mo content is preferably between 0.09% and 0.13%.

[0079] Nb: A key grain-refining element in steel. During hot rolling, niobium strongly inhibits austenite recrystallization and its precipitation within the austenite, pinning the austenite grain boundaries and refining the recrystallized grains. During cooling, niobium continues to precipitate as niobium carbonitrides, significantly refining the microstructure and further improving strength and toughness. Excessive niobium additions increase alloy cost, prevent complete dissolution during normal heating, and negatively impact yield strength. Therefore, niobium precipitation strengthening is recommended within a range of 0.051-0.065%.

[0080] Ti: A nitrogen-binding element in steel, it forms dispersed titanium nitride particles, which inhibit austenite grain coarsening during billet heating and rolling. However, if added too high, coarse carbon / nitride precipitation can easily form in the core of the billet, affecting low-temperature toughness. Therefore, the ideal content is 0.011-0.019%.

[0081] Al: A deoxidizing element in steel. Excessive aluminum can easily increase Al2O3 inclusions in the steel, affecting low-temperature toughness. While ensuring the deoxidation effect, the aluminum content should be minimized. Therefore, the aluminum content is selected to be 0.021-0.049%.

[0082] P: an impurity element in steel. Too high a phosphorus content can easily cause segregation, significantly reducing plasticity and toughness, but too low a phosphorus content can significantly increase steelmaking costs. Therefore, the phosphorus content is preferably ≤ 0.020%. More preferably, in one embodiment, the phosphorus content is preferably 0.0090 to 0.0140%.

[0083] S: An impurity element in steel. It not only increases the hot brittleness of the steel plate but also easily forms MnS inclusions with manganese, reducing the low-temperature toughness of the steel. However, too low a sulfur content increases the steelmaking cost. Therefore, the S content is selected to be ≤ 0.0050%. More preferably, in one embodiment, the S content is preferably 0.0010 to 0.0038%.

[0084] Nitrogen: an impurity element in steel that reduces the plasticity and toughness of the steel plate. Too low nitrogen content will increase steelmaking costs. Therefore, the nitrogen content is selected to be ≤0.0055% ≤0.0055%. More preferably, in one embodiment, the nitrogen content is preferably 0.0021 to 0.0051%.

[0085] In a further preferred embodiment, the chemical composition of the pipeline steel further satisfies a carbon equivalent CEV of 0.352 to 0.420.

[0086] Specifically, carbon equivalent CEV=[C]+[Mn] / 6+([Cr]+[Mo]+[V]) / 5+([Cu]+[Ni]) / 15.

[0087] Among them, [C], [Mn], [Cr], [Mo], [V], [Cu], and [Ni] are the mass percentages of C, Mn, Cr, Mo, V, Cu, and Ni in pipeline steel, respectively.

[0088] For example, if the C content in pipeline steel is 0.050%, then [C] is 0.050; the contents of other elements are deduced similarly and will not be repeated here.

[0089] In terms of technology, Figure 1 The production method includes the following steps: heating the steel billet, temperature-controlled rolling, ultra-fast cooling system water cooling, and natural air cooling.

[0090] Specifically, during the billet heating process, billets with a thickness of ≤320 mm are heated in a heating furnace with a soaking zone temperature of 1150-1220°C and a dwell time of 25-45 minutes. This allows for uniform heating of the billet within the furnace, minimizing the temperature difference between the head, middle, and tail of the billet (for example, the temperature difference between the head, middle, and tail of the billet after exiting the furnace is ≤15°C) and the temperature difference between the top and bottom surfaces (for example, the temperature difference between the top and bottom surfaces of the billet after exiting the furnace is ≤15°C), thus preparing for the subsequent rolling of narrow strength plate.

[0091] In the temperature-controlled rolling process:

[0092] After leaving the heating furnace, the steel billet is first rolled in the recrystallization zone at a rolling temperature of 950-1050°C to obtain an intermediate billet with a thickness of 2t-6t. In this way, by controlling the temperature and thickness of the intermediate billet in the recrystallization zone, the rolling speed in the recrystallization zone can be faster, and the temperature difference between the head, middle and tail of the intermediate billet is small (for example, the temperature difference between the head, middle and tail is ≤20°C) and the temperature difference between the upper and lower surfaces is small (for example, the temperature difference between the upper and lower surfaces is ≤20°C). This avoids inconsistent recrystallized austenite grain size and inconsistent recrystallization degree caused by temperature differences, thereby ensuring the consistency of the recrystallized structure.

[0093] Then, non-recrystallization zone rolling is carried out, and the final rolling temperature is T3-5℃~T3+15℃, to obtain a hot-rolled steel plate with a thickness t of 6 to 60 mm. In this way, fine recrystallized grains can be obtained through non-recrystallization zone rolling, so that the grain size of the hot-rolled steel plate is highly consistent, avoiding inconsistent non-recrystallized austenite grain size and large differences in internal accumulated energy due to temperature differences in the hot-rolled steel plate, thereby laying the foundation for the performance uniformity of the finished steel plate obtained after final cooling.

[0094] Among them, T3 = 910-310[C]-80[Mn]-15[Cr]-80[Mo]; consistent with the previous introduction, [C], [Mn], [Cr], and [Mo] are the mass percentages of C, Mn, Cr, and Mo in pipeline steel, respectively.

[0095] In the water cooling process of the ultra-fast cooling system, the hot-rolled steel plate enters the ultra-fast cooling system for water cooling, and the final cooling temperature is controlled according to the measured C content.

[0096] Specifically, when 0.055%≤C≤0.060%, the final cooling temperature is T4-290℃~T4-270℃; when 0.050%≤C<0.055%, the final cooling temperature is T4-310℃~T4-290℃; when 0.045%≤C<0.050%, the final cooling temperature is T4-330℃~T4-310℃; when 0.040%≤C<0.045%, the final cooling temperature is T4-350℃~T4-330℃; when 0.030%≤C<0.040%, the final cooling temperature is T4-370℃~T4-350℃.

[0097] Among them, T4 = 830-270[C]-90[Mn]-37[Ni]-70[Cr]-83[Mo]; consistent with the previous introduction, [C], [Mn], [Cr], [Mo], and [Ni] are the mass percentages of C, Mn, Cr, Mo, and Ni in pipeline steel, respectively.

[0098] In this way, based on the design of chemical composition, the final cooling temperature in the water cooling process of the ultra-fast cooling system is precisely controlled to reduce the performance fluctuations caused by slight differences in the composition of pipeline steel of the same grade, thereby ensuring the uniformity and stability of performance between different steel plates of the same grade, and achieving the control of the strength difference of different plates of the same grade of pipeline steel.

[0099] In the natural air cooling process, that is, after leaving the ultra-fast cooling system, the steel plate is naturally air-cooled to room temperature on the cooling bed to obtain the finished steel plate.

[0100] Thus, compared with the prior art, the production method of the present invention, on the one hand, does not contain the expensive metal V in terms of chemical composition, and has low addition amounts of alloys such as Ni, Cu, and Mo. Harmful elements such as P, S, and N do not need to be controlled to ultra-low levels, thereby facilitating production and reducing costs. Furthermore, through temperature control during heating, rolling, and cooling, as well as control of other parameters, the process can significantly reduce differences in steel plate structure and properties caused by temperature differences, as well as performance fluctuations caused by slight differences in composition within the same grade of pipeline steel. This ensures the tensile strength, yield strength, yield strength ratio, impact toughness, and drop weight tear resistance of the steel plate, while also ensuring uniformity of performance within the same plate, as well as uniformity and stability of performance between different plates of the same grade, thereby controlling strength differences between different plates of the same grade of pipeline steel. Furthermore, the process avoids the high alloy content chemical composition and inefficient processes such as stacking in the prior art, offering the advantages of low cost and high efficiency. This solves the difficulties in pipeline steel plate production and significantly promotes the development of the pipeline industry.

[0101] For example, in one embodiment, the metallographic structure of the obtained steel plate is a complex phase structure of quasi-polygonal ferrite + acicular ferrite + bainite + tempered bainite, the area of ​​quasi-polygonal ferrite and acicular ferrite accounts for 20 to 45%, and the area of ​​bainite + tempered bainite accounts for 55 to 80%; and the proportion of MA in bainite is ≤30%, and the proportion of MA self-tempering decomposition is ≥30%.

[0102] Here, the metallographic structure of the steel plate can be obtained by conducting a structure test according to the standard GB / T 15125-2009 “Specimens and test methods for metallographic examination of metallic materials”.

[0103] Furthermore, the average grain size of ferrite in the obtained steel sheet was 3 to 6 μm.

[0104] In terms of mechanical strength, the yield strength R t0.5 ≥550MPa, tensile strength R m ≥660MPa, elongation A 50 ≥30%, yield strength ratio ≤0.85; yield strength difference of the same plate ≤40MPa; and among 1000 steel plate products, more than 90% of the steel plates have a yield strength difference of ≤70MPa, and more than 98% of the steel plates have a yield strength difference of ≤90MPa.

[0105] Here, mechanical properties testing can be carried out in accordance with GB / T 228.1-2021 "Tensile tests on metallic materials, Part 1: Room temperature test methods".

[0106] In terms of low-temperature toughness, the obtained steel plate has an impact energy KV2 ≥ 320J at -20°C, an impact energy KV2 ≥ 280J at -40°C, and an impact energy KV2 ≥ 220J at -60°C.

[0107] Here, low-temperature toughness testing can be carried out in accordance with GB / T 229-2007 "Charpy Pendulum Impact Test Method for Metallic Materials".

[0108] In addition, the hardness of the obtained steel plate is ≤245HV10.

[0109] The percentage of the drop weight shear area of ​​DWTT at -10℃ is 100%, the percentage of the drop weight shear area of ​​DWTT at -20℃ is ≥90%, and the ductile-brittle transition temperature of DWTT is lower than -20℃.

[0110] Furthermore, in one embodiment, the steel billet in the production method can be prepared by steelmaking and continuous casting. The specific steelmaking and continuous casting techniques can adopt conventional disclosed techniques in the art.

[0111] Further preferably, in the temperature-controlled rolling process, the intermediate billet can be temperature-controlled cooled by air cooling, water cooling, or a combination of air cooling and water cooling between rolling in the recrystallization zone and rolling in the non-recrystallization zone.

[0112] After the intermediate billet is cooled under controlled temperature and before rolling in the non-recrystallization zone, the temperature difference between the head, middle and tail is ≤25℃.

[0113] In one embodiment, preferably, Figure 1 According to the thickness t of the hot-rolled steel plate, the water cooling process of the ultra-fast cooling system can adopt different process methods.

[0114] Specifically, during the water cooling of the hot-rolled steel plate on the ultra-fast cooling system: if the thickness t of the hot-rolled steel plate is 6-30 mm, the cooling water volume per unit length of the head low-temperature section and the tail low-temperature section of the steel plate is controlled to be smaller than the cooling water volume Q per unit length of the middle section of the steel plate; and if the thickness t of the hot-rolled steel plate is greater than 30 mm, that is, 30 mm < t ≤ 60 mm, the cooling water volume per unit length of the steel plate is constant along the longitudinal direction.

[0115] In this way, by using different water cooling methods according to different thicknesses, the uniformity and stability of performance between steel plates of the same grade and different thicknesses can be greatly improved, and the strength difference of different plates of the same grade of pipeline steel can be controlled; at the same time, through the separate water cooling schemes for thick plates and thin plates, the temperature difference at the head, middle and tail of the cooling process can be reduced, and the uniformity of the organization and performance of the final steel plate product can be ensured, thereby reducing the strength difference of the same plate, and then ensuring the overall strength difference of the same plate and the strength difference of different plates of the same grade of pipeline steel obtained by this production method, and ensuring the overall performance uniformity.

[0116] Here, the cooling water volume per unit length refers to the cooling water volume per unit length along the longitudinal direction of the steel plate, and its unit of measurement is, for example, L / m.

[0117] Furthermore, for the hot-rolled steel plate with a thickness t of 6 to 30 mm, the production method further includes a planning and zoning process located between the temperature-controlled rolling process and the ultra-fast cooling system water cooling process.

[0118] Among them, in the planning zoning process, the entire steel plate is divided into the head low-temperature section, the middle section, and the tail low-temperature section from beginning to end. The sum of the longitudinal lengths of these three sections is the longitudinal length D of the hot-rolled steel plate.

[0119] The “longitudinal direction” mentioned above corresponds to the length direction of the steel plate, that is, the direction defined by the head and tail, which is parallel to the advancing direction of the steel plate on the production line.

[0120] In one embodiment, the longitudinal length D may be between 12 and 54 meters, but is not limited thereto.

[0121] Furthermore, in the planning zoning process, the head low-temperature section is divided into the 1st to nth sub-sections arranged in sequence from the head, and the tail low-temperature section is divided into the 1st to mth sub-sections arranged in sequence from the tail, n≥2, m≥2; accordingly, in the water cooling process of the ultra-fast cooling system, the cooling water volume per unit length of the 1st to nth sub-sections of the head low-temperature section is controlled to increase successively, and the cooling water volume per unit length of the 1st to mth sub-sections of the tail low-temperature section is controlled to increase successively.

[0122] In this way, the longitudinal performance uniformity of the head, middle and tail of each steel plate can be further greatly improved (that is, the performance uniformity of the same plate is improved), and the performance consistency of different steel plates can be guaranteed, so that the performance uniformity of any two steel plates produced can be improved.

[0123] Among them, on the same steel plate, the values ​​of n and m can be the same or different.

[0124] Preferably, n≥3, m≥3.

[0125] Here, the head low-temperature section is divided into the 1st sub-section, ..., the nth sub-section along the longitudinal direction from the head to the middle section, and the nth sub-section is connected to the middle section; similarly, the tail low-temperature section is divided into the 1st sub-section, ..., the mth sub-section along the longitudinal direction from the tail to the middle section, and the mth sub-section is connected to the middle section.

[0126] In one embodiment, in the planning and zoning process, the division of the head low-temperature section, the middle section, and the tail low-temperature section, as well as the division of the 1st to nth sub-sections and the 1st to mth sub-sections, can be divided according to preset lengths; and in a more preferred embodiment, accurate division can be achieved according to the temperature measurement of the hot-rolled steel plate. This embodiment can greatly improve the uniformity of the same plate and the consistency of different plates. This preferred embodiment will be introduced in detail below.

[0127] Specifically, in the planning and zoning process:

[0128] Step S100, measuring the temperature of the hot-rolled steel plate at intervals of 0.2 to 0.5 m along the longitudinal direction from the beginning to the end, and obtaining the temperature measurement results;

[0129] Step S200, the vertical direction is located at D T ~(DD W ) is used to calculate the average temperature T in the middle of the area. Z ;

[0130] Step S300, lower the temperature to below T Z -T T The head section of the steel plate is used as the head low temperature section, and the temperature is lower than T Z -T W The tail section of the steel plate is taken as the tail low-temperature section, and the rest of the sections except the head low-temperature section and the tail low-temperature section are taken as the middle section; wherein, T T and T W Each value is any value between 20 and 50°C;

[0131] Step S400: Divide the head low-temperature section into the 1st to nth sub-sections arranged in sequence from the head according to the measured temperature from low to high, and divide the tail low-temperature section into the 1st to mth sub-sections arranged in sequence from the tail according to the measured temperature from low to high, n≥2, m≥2.

[0132] In step S100, the temperature measurement of the hot-rolled steel plate can be started after all the hot-rolled steel plates leave the hot rolling mill, for example, a temperature measuring device is set between the hot rolling mill and the ultra-fast cooling system and at a position where the distance from the hot rolling mill exceeds D, to measure the temperature of the hot-rolled steel plate, and the tail of the hot-rolled steel plate has already left the hot rolling mill when the temperature is measured; it can also be carried out while the hot-rolled steel plate leaves the hot rolling mill, for example, a temperature measuring device is set at the outlet of the hot rolling mill, or a temperature measuring device is set between the hot rolling mill and the ultra-fast cooling system and at a position where the distance from the hot rolling mill is less than D, to measure the temperature of the hot-rolled steel plate, and at least when the temperature measurement starts at the head of the steel plate, the tail of the steel plate has not yet left the hot rolling mill.

[0133] In step S100, the temperature of the hot-rolled steel plate is measured at a certain distance from the beginning to the end of the hot-rolled steel plate in the range of 0 to D. Here, on the one hand, the value of "certain distance" is 0.2 to 0.5m, that is, for example Figure 2 As shown, the longitudinal distance D between any two adjacent temperature measurement points P It is 0.2~0.5m.

[0134] Preferably, D P 0.2m, 0.25m, 0.3m, 0.35m, 0.4m, 0.45m or 0.5m.

[0135] On the other hand, in step S100, all temperature measurement points are arranged in a straight line along the longitudinal direction.

[0136] Preferably, the transverse width W of the hot-rolled steel plate is such that, in step S100, a point is taken in the transverse middle region W / 3 to 2W / 3 of the hot-rolled steel plate for temperature measurement. More preferably, a point is taken in the transverse middle region W / 2 of the hot-rolled steel plate (i.e., in the center) for temperature measurement. Figure 2 shown.

[0137] Wherein, the transverse direction is perpendicular to the longitudinal direction and the thickness direction of the steel plate.

[0138] In one embodiment, the transverse width W of the hot-rolled steel plate may be in the range of 1 to 4.5 m, but is not limited thereto.

[0139] The temperature measurement result obtained in step S100 will serve as the data basis for the related processing in subsequent steps S200, S300, and S400.

[0140] Specifically, in one embodiment, the temperatures of all the temperature measurement points obtained in step S100 can be directly used as temperature measurement results and substituted into the subsequent steps S200, S300, and S400 for corresponding data processing.

[0141] In a more preferred embodiment, the temperatures of all the temperature measurement points obtained in step S100 can be firstly removed from the abnormal values, and then the temperatures of the remaining temperature measurement points can be used as the temperature measurement results and substituted into the subsequent steps S200, S300, and S400 for corresponding data processing. That is, in this preferred embodiment, step S100 includes:

[0142] Sub-step S101, measuring the temperature of the hot-rolled steel plate at intervals of 0.2 to 0.5 m along the longitudinal direction from the beginning to the end;

[0143] Sub-step S102: removing abnormal values ​​to obtain temperature measurement results.

[0144] In this way, by removing abnormal values, it is possible to avoid abnormal temperature data of individual temperature measurement points affecting the accuracy of subsequent steps S200, S300, and S400.

[0145] Sub-step S102 has multiple implementations. Three different implementations are provided below, but the implementations of step S102 are not limited thereto.

[0146] <First Implementation Method of Sub-step S102>

[0147] If the temperature T of a temperature measuring point Pb Pb The temperature T of an adjacent temperature measuring point Pa Pa Difference |TPa -T Pb | Reach T X1 Above, the temperature T of another adjacent temperature measurement point Pc Pc Difference |T Pc -T Pb |Less than T X2 When , the temperature measuring point Pb is the abnormal value;

[0148] Among them, T X1 The value is 60-80°C, preferably 60-70°C, more preferably 65°C; T X2 The value is 5-15°C, preferably 5-10°C, more preferably 7°C.

[0149] In this way, according to the first implementation method of sub-step S102, all temperature measurement points are checked one by one, and all abnormal values ​​therein are removed. Then, the temperatures of the remaining temperature measurement points are used as the temperature measurement results of step S100 and substituted into the subsequent steps S200, S300, and S400 for corresponding data processing.

[0150] <Second Implementation Method of Sub-step S102>

[0151] If the temperature difference between one temperature measuring point and the temperature of the two adjacent temperature measuring points reaches T X3 For example, the temperature T of a temperature measuring point Pb is Pb The temperature T of an adjacent temperature measuring point Pa Pa Difference |T Pa -T Pb | Reach T X3 Above, the temperature T of another adjacent temperature measurement point Pc Pc Difference |T Pc -T Pb |Also reached T X3 When the value is above , the temperature measurement point Pb is the abnormal value;

[0152] Among them, T X3 The value is 60-80°C, preferably 60-70°C, more preferably 65°C.

[0153] In this way, according to the second implementation of sub-step S102, all temperature measurement points are checked one by one, and all abnormal values ​​therein are removed. Then, the temperatures of the remaining temperature measurement points are used as the temperature measurement results of step S100 and substituted into the subsequent steps S200, S300, and S400 for corresponding data processing.

[0154] <Third Implementation Method of Sub-step S102>

[0155] Based on the data of all temperature measurement points, the temperature is used as the dependent variable and the position as the independent variable to fit the temperature curve of the entire longitudinal length of the steel plate; for example Figure 3 On the temperature curve T=f(D), the longitudinal distance from the temperature measuring point to the head of the steel plate is the horizontal coordinate, and the temperature of the temperature measuring point is the vertical coordinate. In this way, the temperature curve is obtained by fitting based on the coordinates of all the temperature measuring points in the coordinate system. The specific fitting method can adopt the conventional fitting method in mathematical science, which will not be described in detail.

[0156] If the temperature of a measuring point deviates from the temperature curve and reaches T X4 When the temperature is above , the temperature point is determined to be an abnormal value and removed; for example, the temperature T measured by a temperature measuring point Pb is Pb , its coordinates in the coordinate system are (D Pb ,T Pb ), and on the temperature curve T=f(D) position D Pb Corresponding temperature T Pb ', so the temperature T of the temperature measuring point Pb Pb The value of deviation from the temperature curve is |T Pb -T Pb '|, if|T Pb -T Pb '|reach T X4 If the above is true, the temperature measurement point Pb is determined to be an abnormal value and removed;

[0157] Among them, T X4 The value is 60-80°C, preferably 60-70°C, more preferably 65°C.

[0158] In this way, according to the third implementation of sub-step S102, all temperature measurement points are checked one by one, and all abnormal values ​​therein are removed. Then, the temperatures of the remaining temperature measurement points are used as the temperature measurement results of step S100 and substituted into the subsequent steps S200, S300, and S400 for corresponding data processing.

[0159] Next, in step S200, the vertical direction is located at D T ~(DD W ) is used to calculate the average temperature T in the middle of the area. Z .

[0160] That is to say, if Figure 2 As shown, the steel plate is in the entire plate area from 0 to D in the longitudinal direction, excluding 0 to D T The head area (excluding position D T ), (DD W )~D tail area (excluding position DD W ), and the T~(DD W ) is used to calculate the average temperature T in the middle of the area. Z .

[0161] Specifically, the longitudinal direction of D T ~(DD W ) The temperatures of the temperature measuring points in the area are summed and averaged to form the average temperature T Z For example, in D T ~(DD W ) There are h0 temperature measuring points in the area, and the sum of the temperatures of these h0 temperature measuring points is ∑T0. Then the average temperature in the middle is T Z =∑T0 / h0.

[0162] Among them, for the same steel plate, D T and D W The values ​​of can be the same or different; for two different steel plates, D T The values ​​of can be the same or different. W The values ​​can be the same or different.

[0163] D T The value is between 1.5 and 3.5 m, D W The value is between 1.5 and 3.5m.

[0164] Furthermore, D T and D W The values ​​of and decrease in a step-by-step manner as t increases. In this way, the performance consistency of steel plates with different thickness specifications can be further improved, that is, the stability of steel plates with different thickness specifications is strong.

[0165] For example, when t is less than 10 mm, 2.75 m < D T ≤3.5m, preferably D T =3m, 2.75m<D W ≤3.5m, preferably D W =3m.

[0166] When 10mm≤t<15mm, 2.25m<D T ≤2.75m, preferably D T =2.5m, 2.25m<D W ≤2.75m, preferably D W =2.5m.

[0167] When 15mm≤t≤30mm, 1.5m<D T ≤2.25m, preferably D T =2m, 1.5m<D W ≤2.25m, preferably DW =2m.

[0168] Furthermore, in step S300, the temperature is lower than T Z -T T The head section of the steel plate is used as the head low temperature section, and the temperature is lower than T Z -T W The tail section of the steel plate is used as the tail low-temperature section, and the remaining sections except the head low-temperature section and the tail low-temperature section are used as the middle section.

[0169] Among them, the temperature is lower than T Z -T T The head section of the steel plate is the head low temperature section, that is, the section from the beginning of the steel plate in the longitudinal direction is the head low temperature section, with a transverse width of W and a thickness of t; the temperature is lower than T Z -T W The tail section of the steel plate is used as the tail low-temperature section, that is, the section starting from the tail in the longitudinal direction is used as the tail low-temperature section, with a transverse width of W and a thickness of t; except for the head low-temperature section and the tail low-temperature section, the rest of the steel plate is the middle section, with a transverse width of W and a thickness of t.

[0170] Among them, T T and T W The values ​​are the same or different.

[0171] T T The temperature is any value between 20 and 50°C, preferably between 20 and 40°C, and more preferably 30°C.

[0172] T W The temperature is any value between 20 and 50°C, preferably between 20 and 40°C, and more preferably 30°C.

[0173] In specific implementation, step S300 has multiple implementation modes, two of which are provided below. Of course, the present application is not limited thereto.

[0174] <First Implementation Method of Step S300>

[0175] In this embodiment, the head low-temperature section and the middle section are divided by a temperature measuring point; the tail low-temperature section and the middle section are divided by a temperature measuring point.

[0176] like Figure 2 As shown, starting from the beginning in the longitudinal direction of the steel plate, when the temperature measuring point P2 near the plate head is T The temperature is less than T Z -T T , and a temperature measuring point P1 far away from the board head T The temperature reaches T Z -T TWhen the temperature is above 0.05, the temperature measuring point P1 far away from the plate head is used. T In order to divide the low temperature section and the middle section of the head, a temperature measuring point P2 near the head of the plate can be used as a dividing line. T To divide the head into low temperature section and middle section.

[0177] Starting from the tail in the longitudinal direction of the steel plate, when the temperature measuring point P2 near the tail of the plate is W The temperature is less than T Z -T W , and a temperature measuring point P1 far away from the tail of the board W The temperature reaches T Z -T W When the temperature is above 0.05, the temperature measuring point P1 far away from the tail of the board is used. W In order to divide the boundary, the tail low temperature section and the middle section are divided. In a variant embodiment, the temperature measuring point P2 near the tail of the board can also be used. W To divide the boundary, the tail low temperature section and the middle section are divided.

[0178] In the figure, the length of the low temperature section of the head is smaller than the head area 0~D T The length (i.e. length D T ), the length of the tail low temperature section is smaller than the tail area (DD W )~D length (i.e. length D W ); In a variant embodiment, the length of the head low temperature section can be equal to or greater than the head area 0~D T The length of the tail low temperature section can be equal to or greater than the tail area (DD W )~D length.

[0179] <Second Implementation Method of Step S300>

[0180] According to the temperature measurement results, the temperature curve of the entire longitudinal length of the steel plate is fitted with temperature as the dependent variable and position as the independent variable, for example Figure 3 The temperature curve shown in FIG is T=f(D);

[0181] Confirm that within the range of 0 to D / 2, T on the temperature curve Z -T T The corresponding position D TF , and confirm that within the range of D / 2 to D, T on the temperature curve Z -T W The corresponding position D WF ;

[0182] Position D TF and position D WFTo divide the boundaries, the steel plate is divided into a head low-temperature section, a middle section and a tail low-temperature section arranged in sequence from the beginning to the end in the longitudinal direction.

[0183] That is to say, the low temperature section and the middle section of the head are at position D TF To divide the boundary, the tail low temperature section and the middle section are at position D WF The low temperature section of the head occupies the longitudinal direction of the hot-rolled steel plate from 0 to D TF The section has a transverse width W, a thickness t, and a longitudinal length D TF The tail low temperature section occupies the longitudinal direction of the hot rolled steel plate D WF The section from 1 to 2D has a horizontal width W, a thickness t, and a longitudinal length DD. WF The middle section occupies the longitudinal direction of the hot-rolled steel plate D TF ~D WF The section has a transverse width W, a thickness t, and a longitudinal length D WF -D TF .

[0184] exist Figure 3 In, T T and T W The value of T is the same; however, the present invention is not limited thereto. T and T W The value of can also be different.

[0185] Next, in step S400, when dividing the 1st to nth sub-segments and the 1st to mth sub-segments:

[0186] The temperature span of each sub-section does not exceed T Tk , divide the head low temperature section into n sub-sections;

[0187] The temperature span of each sub-section does not exceed T Wk , divide the tail low-temperature section into m sub-segments.

[0188] In this application, the temperature span refers to the difference between the highest temperature and the lowest temperature.

[0189] That is to say, for each of the 1st to nth sub-segments, the highest and lowest temperatures do not exceed T Tk ; For each of the 1st to mth sub-segments, the highest and lowest temperatures do not exceed T Wk .

[0190] As for T Tk 、T Wk The present invention has multiple implementation modes for the specific value of , and several preferred implementation modes are provided below.

[0191] <T Tk 、T WkThe first implementation method of value>

[0192] In this embodiment, Figure 2 Among all the temperature measuring points in the low temperature section of the head, the temperature measuring point P5 T The temperature is the lowest, and the temperature measuring point P5 T The temperature of the entire head low temperature section constitutes the lowest temperature section T of each temperature measuring point T0 .

[0193] Moreover, among all the temperature measuring points in the low temperature section of the head, the temperature measuring point P1 T The temperature is the highest, and the temperature measuring point P1 T The temperature of the entire head low temperature section constitutes the highest temperature T of each temperature measuring point T1 .

[0194] T Tk The highest temperature T among all the temperature measurement points in the low temperature section of the head T1 and the lowest temperature section T T0 Difference T T1 -T T0 1 / n of.

[0195] Thus, the temperature span of each of the 1st to nth sub-segments of the head low temperature section does not exceed (T T1 -T T0 ) / n.

[0196] For example, Figure 2 In the example, n=3, that is, the head low temperature section is divided into 3 sub-sections, namely the first sub-section Z1 T , 2nd sub-segment Z2 T , 3rd sub-segment Z3 T ; First sub-segment Z1 T The temperature span does not exceed (T T1 -T T0 ) / 3, the second sub-segment Z2 T The temperature span does not exceed (T T1 -T T0 ) / 3, the third sub-segment Z3 T The temperature span does not exceed (T T1 -T T0 ) / 3.

[0197] With the third sub-segment Z3 T For a more detailed example, the temperature measurement point P1 T The temperature defines the third sub-segment Z3 T The highest temperature, measuring point P3 T The temperature defines the third sub-segment Z3 T The lowest temperature section, temperature measuring point P1 T and temperature measuring point P3T The temperature difference defines the third sub-segment Z3 T The temperature span does not exceed (T T1 -T T0 ) / 3.

[0198] Similarly, among all the temperature measurement points in the tail low temperature section, the temperature measurement point P5 W The temperature is the lowest, and the temperature measuring point P5 W The temperature of the tail constitutes the lowest temperature section T of each temperature measuring point in the entire tail low temperature section W0 .

[0199] Moreover, among all the temperature measuring points in the tail low temperature section, the temperature measuring point P1 W The temperature is the highest, and the temperature measuring point P1 W The temperature of the entire tail low temperature section constitutes the highest temperature T of each temperature measurement point W1 .

[0200] T Wk The highest temperature T among all the temperature measurement points in the tail low temperature section W1 and the lowest temperature section T W0 Difference T W1 -T W0 1 / m.

[0201] Thus, the temperature span of each of the 1st to mth sub-segments of the tail low temperature section does not exceed (T W1 -T W0 ) / m.

[0202] For example, Figure 2 In the example, m=3, that is, the tail low temperature section is divided into 3 sub-sections, namely the first sub-section Z1 W , 2nd sub-segment Z2 W , 3rd sub-segment Z3 W ; First sub-segment Z1 W The temperature span does not exceed (T W1 -T W0 ) / 3, the second sub-segment Z2 W The temperature span does not exceed (T W1 -T W0 ) / 3, the third sub-segment Z3 W The temperature span does not exceed (T W1 -T W0 ) / 3.

[0203] With the third sub-segment Z3 W For a more detailed example, the temperature measurement point P1 W The temperature defines the third sub-segment Z3 W The highest temperature, measuring point P3 WThe temperature defines the third sub-segment Z3 W The lowest temperature section, temperature measuring point P1 W and temperature measuring point P3 W The temperature difference defines the third sub-segment Z3 W The temperature span does not exceed (T W1 -T W0 ) / 3.

[0204] <T Tk 、T Wk The second implementation method of value>

[0205] In this embodiment, Figure 3 The highest temperature of the temperature curve T=f(D) in the low temperature section of the head is T Z -T T , the corresponding longitudinal position of the steel plate is position D TF .

[0206] And the temperature curve T=f(D) is in the lowest temperature section T in the head low temperature section T0 ', the corresponding longitudinal position of the steel plate is position 0 (that is, the vertical coordinate value when the horizontal coordinate in the coordinate system is 0 is the lowest temperature section T T0 '). Of course, in the variation implementation, the temperature value at position 0 may not be taken as the lowest temperature section T T0 ', but instead take a temperature value slightly greater than 0 as the lowest temperature section T T0 '.

[0207] T Tk The maximum temperature T of the temperature curve T=f(D) in the low temperature section of the head Z -T T and the lowest temperature section T T0 'Difference T Z -T T -T T0 1 / n of '.

[0208] Thus, the temperature span of each of the 1st to nth sub-segments of the head low temperature section does not exceed (T Z -T T -T T0 ') / n.

[0209] For example, Figure 3 In the example, n=2, that is, the head low temperature section is divided into two sub-sections, namely the first sub-section Z1 T , 2nd sub-segment Z2 T ; First sub-segment Z1 T The temperature span does not exceed (T Z -T T -TT0 ') / 2, the second sub-segment Z2 T The temperature span does not exceed (T Z -T T -T T0 ') / 2.

[0210] With the second sub-segment Z2 T For example, the coordinate point (D TF ,T Z -T T ) defines the second sub-segment Z2 T The maximum temperature T Z -T T , coordinate point (D TF1 ,T TF1 ) defines the second sub-segment Z2 T The lowest temperature section T TF1 , thus, the second sub-segment Z2 T Temperature span T Z -T T -T TF1 ≤(T Z -T T -T T0 ') / 2.

[0211] Similarly, the first sub-segment Z1 T Temperature span T TF1 -T T0 '≤(T Z -T T -T T0 ') / 2.

[0212] Furthermore, in one embodiment, among the 1st to nth sub-sections of the head low temperature section, the temperature span of at least the 1st to (n-1)th sub-sections is (T Z -T T -T T0 ') / n, the temperature span of the nth sub-segment ≤ (T Z -T T -T T0 ') / n; or, the temperature span of at least the 2nd to nth sub-segments may be (T Z -T T -T T0 ') / n, the temperature span of the first sub-section ≤ (T Z -T T -T T0 ') / n;

[0213] Similarly, Figure 3 The highest temperature of the temperature curve T=f(D) in the tail low temperature section is TZ -T W , the corresponding longitudinal position of the steel plate is position D WF .

[0214] And the temperature curve T=f(D) is in the lowest temperature section T in the tail low temperature section W0 ', the corresponding longitudinal position of the steel plate is at position D (that is, the vertical coordinate value when the horizontal coordinate in the coordinate system is D is the lowest temperature section T W0 '). Of course, in the variation implementation, the temperature value at position D may not be taken as the lowest temperature section T W0 ', but instead take the temperature value at a position slightly smaller than D as the lowest temperature section T W0 '.

[0215] T Wk The highest temperature T of the temperature curve T=f(D) in the tail low temperature section Z -T W and the lowest temperature section T W0 'Difference T Z -T W -T W0 '1 / m.

[0216] Thus, the temperature span of each of the 1st to mth sub-segments of the tail low temperature section does not exceed (T Z -T W -T W0 ') / m.

[0217] For example, Figure 3 In the example, m=2, that is, the tail low temperature section is divided into two sub-sections, namely the first sub-section Z1 W , 2nd sub-segment Z2 W ; First sub-segment Z1 W The temperature span does not exceed (T Z -T W -T W0 ') / 2, the second sub-segment Z2 W The temperature span does not exceed (T Z -T W -T W0 ') / 2.

[0218] With the second sub-segment Z2 W For example, the coordinate point (D WF ,T Z -T W ) defines the second sub-segment Z2 W The maximum temperature T Z -T W , coordinate point (D WF1 ,TWF1 ) defines the second sub-segment Z2 W The lowest temperature section T WF1 , thus, the second sub-segment Z2 W Temperature span T Z -T W -T WF1 ≤(T Z -T W -T W0 ') / 2.

[0219] Similarly, the first sub-segment Z1 W Temperature span T WF1 -T W0 '≤(T Z -T W -T W0 ') / 2.

[0220] Furthermore, in one embodiment, among the 1st to mth sub-sections of the tail low temperature section, the temperature span of at least the 1st to (m-1)th sub-sections is (T Z -T W -T W0 ') / m, the temperature span of the mth sub-segment ≤ (T Z -T W -T W0 ') / m; or, the temperature span of at least the 2nd to mth sub-segments may be (T Z -T W -T W0 ') / m, the temperature span of the first sub-section ≤(T Z -T W -T W0 ') / m.

[0221] <T Tk 、T Wk The third implementation method of value>

[0222] In this embodiment, T Tk Predetermine the temperature span T n , which is preferably any value between 5 and 20°C, for example, 10°C; T Wk Predetermine the temperature span T m , which is preferably any value between 5 and 20°C, for example, 10°C.

[0223] That is, the temperature span of each of the 1st to nth sub-segments of the head low temperature section does not exceed T n ; The temperature span of each of the 1st to mth sub-segments of the tail low temperature section does not exceed T m .

[0224] Thus, in one embodiment, when each sub-segment is divided based on the temperature measurement point as the dividing boundary, Figure 2 For example:

[0225] In the head low temperature section, the first sub-section Z1 T The temperature difference between any two temperature measuring points does not exceed T n , the second sub-segment Z2 T The temperature difference between any two temperature measuring points does not exceed T n , the third sub-segment Z3 T The temperature difference between any two temperature measuring points does not exceed T n , such as temperature measurement point P1 T and temperature measuring point P3 T The temperature difference defines the third sub-segment Z3 T The temperature span does not exceed T n ;

[0226] Similarly, in the tail low temperature section, the first sub-section Z1 W The temperature difference between any two temperature measuring points does not exceed T m , the second sub-segment Z2 W The temperature difference between any two temperature measuring points does not exceed T m , the third sub-segment Z3 W The temperature difference between any two temperature measuring points does not exceed T m , such as temperature measurement point P1 W and temperature measuring point P3 W The temperature difference defines the third sub-segment Z3 W The temperature span does not exceed T m .

[0227] In a variation of the embodiment, when the temperature curve is fitted with the temperature measurement result, Figure 3 For example:

[0228] In the head low temperature section, the first sub-section Z1 T Temperature span T TF1 -T T0 '≤T n , the second sub-segment Z2 T Temperature span T Z -T T -T TF1 ≤T n ;

[0229] Similarly, in the tail low temperature section, the first sub-section Z1 W Temperature span T WF1 -T W0 '≤T m , the second sub-segment Z2W Temperature span T Z -T W -T WF1 ≤T m ;

[0230] Furthermore, in this variation, among the 1st to nth sub-sections of the head low-temperature section, the temperature span of at least the 1st to (n-1)th sub-sections may be T n , the temperature span of the nth sub-segment ≤ T n Alternatively, the temperature span of at least the 2nd to nth sub-segments may be T n , the temperature span of the first sub-section ≤ T n ;

[0231] Similarly, in the 1st to mth sub-segments of the tail low-temperature section, the temperature span of at least the 1st to (m-1)th sub-segments may be T m , the temperature span of the mth sub-segment ≤ T m Alternatively, the temperature span of at least the 2nd to mth sub-segments may be T m , the temperature span of the first sub-segment ≤ T m .

[0232] Next, in step S400, <T Tk 、T Wk The first implementation method of taking value>, <T Tk 、T Wk The third implementation method of taking the value> is adapted. In the 1st to nth sub-segments, two adjacent sub-segments can be specifically divided by a temperature measuring point; in the 1st to mth sub-segments, two adjacent sub-segments can be specifically divided by a temperature measuring point.

[0233] For example, in one embodiment, starting from the first temperature measuring point near the plate head in the low temperature section of the head, when the temperature difference between the temperature of one temperature measuring point near the plate head and the lowest temperature section of the sub-section does not exceed T Tk , and the temperature difference between a temperature measuring point far away from the plate head and the lowest temperature section of the sub-section exceeds T Tk When , the sub-section and the next sub-section are divided by taking the temperature measuring point close to the plate head as the dividing boundary;

[0234] For example, Figure 2 , two adjacent temperature measurement points P6 T 、P4 T If the temperature measurement point P6 near the board head is T The temperature of this sub-segment Z1 T The lowest temperature section (i.e. temperature measuring point P5 T The temperature difference does not exceed TTk , and the temperature measurement point P4 far away from the board head T The temperature of this sub-segment Z1 T The lowest temperature section (i.e. temperature measuring point P5 T The temperature difference exceeds T Tk When the temperature is measured at point P6 T To divide the boundary, divide the sub-segment Z1 T and the next sub-segment Z2 T ; And so on, until we reach the temperature measuring point P1 farthest from the board head in the low temperature section of the head. T , completing the division of the 1st to nth sub-segments.

[0235] Similarly, starting from the first temperature measuring point near the tail of the tail low temperature section, when the temperature difference between the temperature of the temperature measuring point near the tail of the board and the lowest temperature section of the sub-section does not exceed T Wk , and the temperature difference between a temperature measuring point far away from the tail of the board and the lowest temperature section of the sub-section exceeds T Wk When the temperature of the sub-section is 0.05, the temperature measuring point near the tail of the board is used as the dividing line to divide the sub-section and the next sub-section;

[0236] For example, Figure 2 , two adjacent temperature measurement points P6 W 、P4 W If the temperature measurement point P6 near the tail of the board W The temperature of this sub-segment Z1 W The lowest temperature section (i.e. temperature measuring point P5 W The temperature difference does not exceed T Wk , and the temperature measurement point P4 far away from the tail of the board W The temperature of this sub-segment Z1 W The lowest temperature section (i.e. temperature measuring point P5 W The temperature difference exceeds T Wk When the temperature is measured at point P6 W To divide the boundary, divide the sub-segment Z1 W and the next sub-segment Z2 W ; And so on, until we reach the temperature measuring point P1 at the tail low temperature section, which is farthest from the tail. W , completing the division of the 1st to mth sub-segments.

[0237] Of course, in a simple variation, the first temperature measurement point (e.g. Figure 2 Middle temperature measuring point P1 T ) starts, when two adjacent temperature measurement points (such as Figure 2 Temperature measurement point P3 T 、P4 T), a temperature measuring point near the center of the plate (e.g. Figure 2 Temperature measurement point P3 T The difference between the temperature of the sub-section and the lowest temperature section of the sub-section does not exceed T Tk , and a temperature measuring point far away from the center of the plate (for example Figure 2 Temperature measurement point P4 T ) exceeds T Tk When the temperature is measured at a point close to the center of the plate (e.g. Figure 2 Temperature measurement point P3 T ) is the dividing line to divide the sub-segment (for example Figure 2 Subsegment Z3 in T ) and the next subsection (e.g. Figure 2 Subsegment Z2 in T ); and so on, until the temperature measuring point P5 farthest from the center of the plate in the head low temperature section T , complete the division of the 1st to nth sub-segments;

[0238] You can also measure the temperature from the first temperature measuring point closest to the center of the plate in the tail low temperature section (for example Figure 2 Middle temperature measuring point P1 W ) starts, when two adjacent temperature measurement points (such as Figure 2 Temperature measurement point P3 W 、P4 W ), a temperature measuring point near the center of the plate (e.g. Figure 2 Temperature measurement point P3 W The difference between the temperature of the sub-section and the lowest temperature section of the sub-section does not exceed T Wk , and a temperature measuring point far away from the center of the plate (for example Figure 2 Temperature measurement point P4 W ) exceeds T Wk When the temperature is measured at a point close to the center of the plate (e.g. Figure 2 Temperature measurement point P3 W ) is the dividing line to divide the sub-segment (for example Figure 2 Subsegment Z3 in W ) and the next subsection (e.g. Figure 2 Subsegment Z2 in W ); and so on, until the temperature measuring point P5 at the tail low temperature section is farthest from the center of the plate. W , completing the division of the 1st to mth sub-segments.

[0239] Next, in the water cooling process of the ultra-fast cooling system, the cooling water volume per unit length of the 1st to nth sub-sections is k1 to k n times.

[0240] That is, in the head low temperature section, the cooling water volume per unit length of the first sub-section is k1 times Q; the cooling water volume per unit length of the second sub-section is k2 times Q; ...; the cooling water volume per unit length of the nth sub-section is k times Q. n times.

[0241] Among them, k1~k n The value ranges from 0.55 to 0.98.

[0242] Preferably, when n≥3, k1~k n Set to arithmetic increments.

[0243] Similarly, the cooling water volume per unit length of the 1st to mth sub-sections is K1 to K m times.

[0244] That is, in the tail low temperature section, the cooling water volume per unit length of the first sub-section is K1 times of Q; the cooling water volume per unit length of the second sub-section is K2 times of Q; ...; the cooling water volume per unit length of the mth sub-section is K n times.

[0245] Among them, K1~K m The value ranges from 0.50 to 0.95.

[0246] Preferably, when m≥3, K1~K m Set to arithmetic increments.

[0247] In one embodiment, k1 to k n The values ​​of K1~K m The values ​​of k1 to k2 increase with the increase of t. Thus, for two steel plates with different thicknesses t, the corresponding k1 to k3 can be used. n 、K1~K m Carry out cooling control to improve the performance uniformity of different steel plates.

[0248] In one embodiment, when t is less than 10 mm, k1 to k n The value ranges from 0.55 to 0.85, K1 to K m The value is between 0.50 and 0.80; when 10mm≤t<15mm, k1~k n The value ranges from 0.70 to 0.90, K1 to K m The value is between 0.65 and 0.85; when 15mm≤t≤30mm, k1~k n The value ranges from 0.80 to 0.98, K1 to K m The value ranges from 0.75 to 0.95.

[0249] For example, taking n=m=3 as an example, when the value of t is less than 10mm:

[0250] k1 is set between 0.55 and 0.65, that is, the cooling water volume per unit length of the first subsection of the head low-temperature section is (0.55 to 0.65) Q;

[0251] k2 takes a value of 0.65-0.75, that is, the cooling water volume per unit length of the second sub-section of the head low-temperature section is (0.65-0.75)Q;

[0252] k3 is set between 0.75 and 0.85, that is, the cooling water volume per unit length of the third subsection of the head low-temperature section is (0.75 to 0.85) Q;

[0253] K1 is set at 0.50-0.60, that is, the cooling water volume per unit length of the first sub-section of the tail low-temperature section is (0.50-0.60)Q;

[0254] K2 is set at 0.60-0.70, that is, the cooling water volume per unit length of the second sub-section of the tail low-temperature section is (0.60-0.70)Q;

[0255] The value of K3 is between 0.70 and 0.80, that is, the cooling water volume per unit length of the third sub-section of the tail low-temperature section is (0.70 to 0.80) Q.

[0256] Taking n=m=3 as an example, when 10mm≤t<15mm:

[0257] k1 is set between 0.70 and 0.80, that is, the cooling water volume per unit length of the first subsection of the head low-temperature section is (0.70 to 0.80) Q;

[0258] k2 takes a value of 0.80-0.85, that is, the cooling water volume per unit length of the second subsection of the head low-temperature section is (0.80-0.85)Q;

[0259] k3 is set between 0.85 and 0.90, that is, the cooling water volume per unit length of the third subsection of the head low-temperature section is (0.85 to 0.90) Q;

[0260] K1 is set at 0.65~0.75, that is, the cooling water volume per unit length of the first sub-section of the tail low-temperature section is (0.65~0.75)Q;

[0261] K2 is set at 0.75-0.80, that is, the cooling water volume per unit length of the second sub-section of the tail low-temperature section is (0.75-0.80)Q;

[0262] The value of K3 is between 0.80 and 0.85, that is, the cooling water volume per unit length of the third sub-section of the tail low-temperature section is (0.80 to 0.85) Q.

[0263] Taking n=m=3 as an example, when 15mm≤t≤30mm:

[0264] k1 is set between 0.80 and 0.87, that is, the cooling water volume per unit length of the first subsection of the head low-temperature section is (0.80 to 0.87) Q;

[0265] k2 takes a value of 0.87 to 0.92, that is, the cooling water volume per unit length of the second subsection of the head low-temperature section is (0.87 to 0.92) Q;

[0266] k3 is set between 0.92 and 0.98, that is, the cooling water volume per unit length of the third subsection of the head low-temperature section is (0.92 to 0.98) Q;

[0267] K1 is set at 0.75~0.85, that is, the cooling water volume per unit length of the first sub-section of the tail low-temperature section is (0.75~0.85)Q;

[0268] K2 is set at 0.85-0.90, that is, the cooling water volume per unit length of the second sub-section of the tail low-temperature section is (0.85-0.90)Q;

[0269] The value of K3 is between 0.90 and 0.95, that is, the cooling water volume per unit length of the third sub-section of the tail low-temperature section is (0.90 to 0.95) Q.

[0270] Furthermore, the ultra-fast cooling system usually includes 24 groups of headers, each group of headers can spray water on the steel plate to cool the steel plate. The longitudinal length covered by each group of headers is about 1m. In actual implementation, the water spraying volume of each group of headers can be regulated or shielded to adjust the cooling water volume per unit length at each section of the steel plate.

[0271] In summary, the production method of pipeline steel according to the present invention can not only improve performance uniformity and reduce strength differences between the same and different steel plates, but also avoid inefficient processes such as high alloy content chemical composition and stacking in the prior art. It has the advantages of low cost and high efficiency, can solve the difficulties in the field of pipeline steel plate production, and greatly promote the development of the pipeline industry.

[0272] Several embodiments of the present invention are provided below to more specifically illustrate the technical purpose of the present invention.

[0273] These embodiments respectively provide a finished pipeline steel plate. The chemical composition of each steel plate is shown in Table 1.

[0274] [Table 1]

[0275]

[0276] The steel plates of various examples were sampled and tested, and the test results are as follows:

[0277] (1) In each embodiment, the metallographic structure is a complex phase structure of quasi-polygonal ferrite + acicular ferrite + bainite + tempered bainite, the area of ​​quasi-polygonal ferrite and acicular ferrite accounts for 20-45%, and the area of ​​bainite + tempered bainite accounts for 55-80%; and the proportion of MA in bainite is ≤30%, and the proportion of MA self-tempering decomposition is ≥30%;

[0278] (2) In each embodiment, the average grain size of ferrite in the steel plate is 3 to 6 μm;

[0279] (3) The mechanical properties, low temperature toughness and hardness of the steel plates of each embodiment are shown in Table 2;

[0280] (4) In each embodiment, the -10°C DWTT drop weight shear area percentage of the steel plate is 100%, the -20°C DWTT drop weight shear area percentage is ≥90%, and the DWTT ductile-brittle transition temperature is lower than -20°C.

[0281] [Table 2]

[0282]

[0283]

[0284] The preparation process of the steel plates in each embodiment is roughly as follows:

[0285] (1) The continuous casting billet (thickness ≤ 320 mm) prepared by steelmaking and continuous casting is heated in a heating furnace with a soaking zone temperature of 1150-1220° C. and a residence time of 25-45 min;

[0286] (2) After leaving the heating furnace, the steel slab is first rolled in the recrystallization zone at a rolling temperature of 950-1050°C to obtain an intermediate slab with a thickness of 2t-6t; then rolled in the non-recrystallization zone to obtain a hot-rolled steel plate; wherein the final rolling temperature of the non-recrystallization zone rolling, the thickness t and the longitudinal length D of the hot-rolled steel plate are shown in Table 3 respectively;

[0287] [Table 3]

[0288] Finish rolling temperature, ℃ t,mm D,m Final cooling temperature, ℃ Example 1 760 9 45 285 Example 2 758 15 47 280 Example 3 758 23 46 305 Example 4 755 25 46 325 Example 5 755 28 45 345 Example 6 753 30 42 360 Example 7 753 39 41 365

[0289] (3) For the hot-rolled steel plates of Examples 1 to 6, the temperature of each point was measured at intervals of 0.2 to 0.5 m from the head to the tail in the longitudinal direction to obtain the temperature measurement results; based on the temperature measurement results, the head low-temperature section was divided into the 1st to nth sub-sections arranged in sequence from the head, and the tail low-temperature section was divided into the 1st to mth sub-sections arranged in sequence from the tail according to the measured temperatures from low to high;

[0290] (4) The hot-rolled steel plates of each embodiment enter the ultra-fast cooling system for water cooling, and the final cooling temperature is shown in Table 3. Furthermore, during the cooling period, the cooling water volume per unit length of the steel plate of Example 7 remains constant along the longitudinal direction. In Examples 1 to 6, the cooling water volume per unit length Q of the middle section is used as the standard, and the cooling water volume per unit length of the 1st to nth sub-sections of the head low-temperature section is controlled to increase successively and be less than Q, and the cooling water volume per unit length of the 1st to mth sub-sections of the tail low-temperature section is controlled to increase successively and be less than Q.

[0291] (5) After exiting the ultra-fast cooling system, the steel plates of each embodiment are naturally air-cooled to room temperature on a cooling bed to obtain finished steel plates.

Claims

1. A method for producing high-strength pipeline steel plate, characterized in that: The chemical composition of the pipeline steel includes, by mass percentage, C 0.030-0.060%, Si 0.16-0.24%, Mn 1.61-1.69%, Cr 0.14-0.18%, Ni 0.11-0.16%, Cu 0.01-0.08%, Mo 0.09-0.13%, Nb 0.051-0.065%, Ti 0.011-0.019%, Al 0.021-0.049%, P≤0.020%, S≤0.0050%, N≤0.0055%, and the remainder is iron and unavoidable impurities; The production method comprises: The steel billet with a thickness of ≤320mm is heated in a heating furnace with a soaking temperature of 1150~1220℃ and a dwell time of 25~45min. After leaving the heating furnace, the steel slab is first rolled in the recrystallization zone at a rolling temperature of 950-1050°C to obtain an intermediate slab with a thickness of 2t-6t. It is then rolled in the non-recrystallization zone at a finishing temperature of T3-5°C to T3+15°C to obtain a hot-rolled steel plate with a thickness of 6-30mm. Where T3 = 910-310[C]-80[Mn]-15[Cr]-80[Mo]. The hot rolled steel plate enters the ultra-fast cooling system for water cooling, and the final cooling temperature is controlled according to the measured C content; when 0.055%≤C≤0.060%, the final cooling temperature is T4-290℃~T4-270℃; when 0.050%≤C<0.055%, the final cooling temperature is T4-310℃~T4-290℃; when 0.045%≤C<0.050%, the final cooling temperature is T4-310℃~T4-290℃; T4-330℃~T4-310℃; when 0.040%≤C<0.045%, the final cooling temperature is T4-350℃~T4-330℃; when 0.030%≤C<0.040%, the final cooling temperature is T4-370℃~T4-350℃; where T4=830-270[C]-90[Mn]-37[Ni]-70[Cr]-83[Mo]; After leaving the ultra-fast cooling system, the steel plate is naturally air-cooled to room temperature on the cooling bed to obtain the finished steel plate; Wherein, [C], [Mn], [Cr], [Mo], and [Ni] are the mass percentages of C, Mn, Cr, Mo, and Ni in pipeline steel, respectively; During the water cooling of the hot-rolled steel plate in the ultra-fast cooling system: the cooling water volume per unit length of the head low-temperature section and the tail low-temperature section of the steel plate is controlled to be less than the cooling water volume Q per unit length of the middle section of the steel plate; the head low-temperature section is divided into the 1st to nth sub-sections arranged in sequence from the head, and the tail low-temperature section is divided into the 1st to mth sub-sections arranged in sequence from the tail, n≥2, m≥2; the cooling water volume per unit length of the 1st to nth sub-sections of the head low-temperature section is controlled to increase sequentially, and the cooling water volume per unit length of the 1st to mth sub-sections of the tail low-temperature section is controlled to increase sequentially.

2. The method for producing high-strength pipeline steel plate according to claim 1, wherein: The chemical composition of the pipeline steel includes, by mass percentage, P 0.0090-0.0140%, S 0.0010-0.0038%, and N 0.0021-0.0051%.

3. The method for producing high-strength pipeline steel plate according to claim 1, characterized in that: In the chemical composition of the pipeline steel, CEV=[C]+[Mn] / 6+([Cr]+[Mo]+[V]) / 5+([Cu]+[Ni]) / 15 is 0.352~0.420; Among them, [C], [Mn], [Cr], [Mo], [V], [Cu], and [Ni] are the mass percentages of C, Mn, Cr, Mo, V, Cu, and Ni in pipeline steel, respectively.

4. The method for producing high-strength pipeline steel plate according to claim 1, characterized in that: The production method further comprises: Before entering the ultra-fast cooling system, the temperature of the hot-rolled steel plate is measured at intervals of 0.2 to 0.5 m along the longitudinal direction from the beginning to the end, and the temperature measurement results are obtained; The vertical position is D T ~(DD W ) is used to calculate the average temperature T in the middle of the area. Z ; Where D is the longitudinal length of the hot-rolled steel plate, D T The value is between 1.5 and 3.5 m, D W The value is between 1.5 and 3.5m; Lower the temperature below T Z -T T The head section of the steel plate is used as the head low temperature section, and the temperature is lower than T Z -T W The tail section of the steel plate is taken as the tail low-temperature section, and the rest of the sections except the head low-temperature section and the tail low-temperature section are taken as the middle section; wherein, T T and T W Each value is any value between 20~50℃.

5. The method for producing high-strength pipeline steel plate according to claim 4, characterized in that: The transverse width W of the hot-rolled steel plate; In the step of "measuring the temperature of the hot-rolled steel plate at intervals of 0.2 to 0.5 m along the longitudinal direction from the beginning to the end", the temperature is measured at points in the W / 3 to 2W / 3 area in the transverse middle of the hot-rolled steel plate, and all the temperature measuring points are arranged in a straight line along the longitudinal direction.

6. The method for producing high-strength pipeline steel plate according to claim 4, characterized in that: D T and D W The values ​​of decrease in a step-by-step manner as t increases; When t<10mm, 2.75m<D T ≤3.5m, 2.75m<D W ≤3.5m; When 10mm≤t<15mm, 2.25m<D T ≤2.75m, 2.25m<D W ≤2.75m; When 15mm≤t≤30mm, 1.5m<D T ≤2.25m, 1.5m<D W ≤2.25m.

7. The method for producing high-strength pipeline steel plate according to claim 4, characterized in that: In the step "Before entering the ultra-fast cooling system, the temperature of the hot-rolled steel plate is measured at intervals of 0.2 to 0.5 m along the longitudinal direction from the beginning to the end to obtain the temperature measurement results": The temperature of the hot-rolled steel plate is measured at intervals of 0.2 to 0.5 m along the longitudinal direction from the beginning to the end; Remove outliers and get the temperature measurement results; Among them, if the temperature difference between one temperature measuring point and the temperature of an adjacent temperature measuring point reaches T X1 Above, the temperature difference with another adjacent temperature measuring point is less than T X2 When , the temperature measurement point is the abnormal value; wherein, T X1 The value is between 60~80℃, T X2 The value is between 5~15℃; Or, if the temperature difference between one temperature measuring point and the temperature of two adjacent temperature measuring points reaches T X3 When the temperature is above , the temperature measurement point is the abnormal value; wherein, T X3 The value is between 60~80℃; Alternatively, all the temperature measurement points are used as the data basis, and the temperature is used as the dependent variable and the position is used as the independent variable to fit the temperature curve of the entire longitudinal length of the steel plate. If the temperature of a temperature measurement point deviates from the temperature curve by T X4 When the value is above , the temperature measurement point is determined to be an abnormal value and removed; X4 The value is between 60~80℃.

8. The method for producing high-strength pipeline steel plate according to claim 4, characterized in that: Step "lower the temperature below T Z -T T The head section of the steel plate is used as the head low temperature section, and the temperature is lower than T Z -T W The tail section of the steel plate is used as the tail low-temperature section, and the remaining sections except the head low-temperature section and the tail low-temperature section are used as the middle section. Starting from the beginning in the longitudinal direction of the steel plate, when the temperature of the temperature measuring point close to the plate head among the two adjacent temperature measuring points is less than T Z -T T , and the temperature of a temperature measuring point far away from the plate head reaches T Z -T T When the temperature is above 0.05, one of the two adjacent temperature measurement points is used as the dividing line to divide the longitudinally arranged head low temperature section and middle section; Starting from the tail in the longitudinal direction of the steel plate, when the temperature of the temperature measuring point near the tail of the plate is lower than T Z -T W , and the temperature of a temperature measuring point far away from the tail reaches T Z -T W When the temperature is above 0.05, one of the two adjacent temperature measuring points is used as the dividing line to divide the longitudinally arranged tail low-temperature section and middle section.

9. The method for producing high-strength pipeline steel plate according to claim 4, characterized in that: Step "lower the temperature below T Z -T T The head section of the steel plate is used as the head low temperature section, and the temperature is lower than T Z -T W The tail section of the steel plate is used as the tail low-temperature section, and the remaining sections except the head low-temperature section and the tail low-temperature section are used as the middle section. According to the temperature measurement results, the temperature curve of the entire longitudinal length of the steel plate is fitted with temperature as the dependent variable and position as the independent variable; Confirm that within the range of 0~D / 2, T on the temperature curve Z -T T The corresponding position D TF , and confirm that within the D / 2~D range, T on the temperature curve Z -T W The corresponding position D WF ; Position D TF and position D WF To divide the boundaries, the steel plate is divided into a head low-temperature section, a middle section and a tail low-temperature section arranged in sequence from the beginning to the end in the longitudinal direction.

10. The method for producing high-strength pipeline steel plate according to claim 4, characterized in that: In the step "the head low-temperature section is divided into the 1st to nth sub-sections arranged sequentially from the head, and the tail low-temperature section is divided into the 1st to mth sub-sections arranged sequentially from the tail, n ≥ 2, m ≥ 2": The temperature span of each sub-section does not exceed T Tk , divide the head low temperature section into n sub-sections; The temperature span of each sub-section does not exceed T Wk , divide the tail low temperature section into m sub-sections; Among them, T Tk The highest temperature T among all the temperature measurement points in the low temperature section of the head T1 and the lowest temperature section T T0 Difference T T1 -T T0 1 / n of the temperature curve, or the highest temperature T in the low temperature section of the head Z -T T and the lowest temperature section T T0 'Difference T Z -T T -T T0 ', or the predetermined value T of the temperature span n ; T Wk The highest temperature T among all the temperature measurement points in the tail low temperature section W1 and the lowest temperature section T W0 Difference T W1 -T W0 1 / m, or the highest temperature T in the tail low temperature section of the temperature curve Z -T W and the lowest temperature section T W0 'Difference T Z -T W -T W0 '1 / m, or the predetermined value of temperature span T m ; The temperature curve is obtained by fitting based on the temperature measurement results, with temperature as the dependent variable and position as the independent variable; T n and T m Each value is any value between 5~20℃.

11. The method for producing high-strength pipeline steel plate according to claim 1, characterized in that: In the step "During the water cooling process on the ultra-fast cooling system, the cooling water volume per unit length of the first to nth sub-sections of the head low-temperature section is controlled to increase sequentially, and the cooling water volume per unit length of the first to mth sub-sections of the tail low-temperature section is controlled to increase sequentially", The cooling water volume per unit length of the 1st to nth sub-sections is k1~k of Q respectively. n times; among them, k1~k n The value ranges from 0.55 to 0.98; The cooling water volume per unit length of the 1st to mth sub-sections is K1~K m times; among them, K1~K m The value ranges from 0.50 to 0.

95.

12. The method for producing high-strength pipeline steel plate according to claim 11, characterized in that: k1~k n The value of K1~K m The values ​​of increase with the increase of t; When t is less than 10 mm, k1~k n The value ranges from 0.55 to 0.85, K1 to K m The value ranges from 0.50 to 0.80; When 10mm≤t<15mm, k1~k n The value ranges from 0.70 to 0.90, K1 to K m The value ranges from 0.65 to 0.85; When 15mm≤t≤30mm, k1~k n The value ranges from 0.80 to 0.98, K1 to K m The value is between 0.75 and 0.

95.

13. The method for producing high-strength pipeline steel plate according to claim 12, characterized in that: When t is less than 10 mm, n=m=3, k1 is between 0.55 and 0.65, k2 is between 0.65 and 0.75, k3 is between 0.75 and 0.85, K1 is between 0.50 and 0.60, K2 is between 0.60 and 0.70, and K3 is between 0.70 and 0.80; When 10mm≤t<15mm, n=m=3, k1 is between 0.70~0.80, k2 is between 0.80~0.85, k3 is between 0.85~0.90, K1 is between 0.65~0.75, K2 is between 0.75~0.80, and K3 is between 0.80~0.85; When 15mm≤t≤30mm, n=m=3, k1 is between 0.80~0.87, k2 is between 0.87~0.92, k3 is between 0.92~0.98, K1 is between 0.75~0.85, K2 is between 0.85~0.90, and K3 is between 0.90~0.95.

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